AB163. SOH21AS160. May-Thurner syndrome: a case series—is the incident as low as we think?

Background: May-Thurner syndrome (MTS) is an uncommon condition leading to venous outflow obstruction resulting from extrinsic venous compression by the arterial system against bony structures. The prevalence of MTS was thought to be rare when first described, and even today the incidence is still relatively unknown. It is thought that MTS causes only between 2–5% of deep vein thrombosis (DVT), but its prevalence may be widely underestimated. We present three cases of MTS with DVT, all with differing risk factors.

Methods: Three patients presented to University Hospital Limerick (UHL) with acute onset unilateral left leg swelling and pain. MTS was an incidental finding in two of the cases following CT. Two patients were managed medically with anticoagulation. They both re-presented with pain and no improvement in swelling, and were treated with catheter-directed thrombolysis (CDT). The third patient was sent for thrombolysis immediately. They are all pending investigation for venous insufficiency post-discharge.

Results: In cases of DVT or pulmonary embolism, patients can often be diagnosed and treated without further investigation, particularly if they have risk factors for the same. If there is high suspicion of MTS, additional imaging should be undertaken. In MTS with DVT, recommended management is therapeutic anticoagulation, CDT and ultrasound. If anticoagulation alone is used, studies have shown that patients respond poorly, as seen in our cases.

Conclusions: We hope to highlight that the prevalence of MTS may be much higher than anticipated, and that identification of the pathology may alter the management in DVT presenting with minimal risk factors.

Keywords: Anticoagulation; catheter-directed thrombolysis (CDT); deep vein thrombosis (DVT); May-Thurner syndrome (MTS); venous outflow obstruction